The present invention relates generally to wood panels made out of veneer sheets and to the methods of fabricating such panels and, more particularly, to a thin wood laminate panel made out of one or more wood veneer sheets having apertures passing through the panel spaced equidistant apart along the sides of the panel in order to decrease warping of the panel.
In the past, various methods have been used to reinforce veneer or to help keep the veneer from splitting or cracking. For example, U.S. Pat. No. 1,744,203, issued to Becker on Jan. 21, 1938, describes a method of decreasing splitting or minimizing expansion or contraction during drying of veneer by stitching layers or sheets of wet or green veneer at right angles to the grains of the wood and parallel to and spaced at some distance from the longest sides of the veneer sheets. Any number of parallel rows of stitching may be used. U.S. Pat. No. 3,856,600, issued to Fields on Dec. 24, 1974, discloses a method of sewing together with parallel rows of thread or fiber cord green sheets of veneer assembled side by side. The thread is stitched in rows spaced from edges of the sheets and across (transverse to) the wood grain and is chosen so that it shrinks at about the same rate as the green veneer during subsequent drying of the veneer. The dried stitched sheets of veneer are later used to manufacture plywood panels. A method of reinforcing a veneer sheet is described in U.S. Pat. No. 4,269,883, issued to Hasegawa on May 26, 1981. A cord is thrust through the veneer sheet at different intervals and intermediate ends of splits in the sheet and the projecting portions of the cord are formed into fastening means by melting or deforming the projecting portions, or applying an adhesive to the portions in order to prevent the cord from pulling free of the sheet. Cords are shown positioned parallel to a side of the veneer sheet, and in a zigzag fashion along cracks or splits in the sheet.
U.S. Pat. No. 2,018,712, issued to Elmendorf on Oct. 29, 1935, describes a method of treating a wood panel or sheet of wood to minimize warping by cutting part way through the thickness of the panel or sheet parallel to the wood grain providing a number of narrow strips held together- by connecting webs of wood. The sheet or panel is then stressed across the grain causing the webs to divide into small strands. The gaps between the narrow strips may then be filled with elastic material which bonds to the wood, such as rubber latex, allowing the panels to expand and contract. Continuous surface panels on a door frame cover a core having uniformly distributed perforations throughout the core body are provided to prevent warpage due to changes in temperature and humidity conditions, are described in U.S. Pat. No. 2,214,675, issued to Jensen on Sept. 10, 1940. Finally, French Patent No. 882,675, issued to Couelle and dated June 10, 1943, discloses the use of pegs forced into apertures in planks of wood.
One of the conventional methods used today for manufacture of wood veneer includes seasoning hardwood or logs in a predryer, cutting the wood veneer sheets from the hardwood, drying the veneer sheets in kilns, and then hot plate pressing the cut veneer sheets. However, such processing of wood veneer sheets may not eliminate the dimensional instability or warping of the sheet caused by moisture in the wood veneer and variable moisture content in the ambient atmosphere. There may still exist differences in the vapor pressures and temperatures existing in the several components of a laminate panel and particularly in the veneer sheets and in the ambient atmosphere. The continuous seeking of equilibrium or balance between the moisture in the laminate panel and in atmosphere may cause dimensional instability of the laminate panel as usually evidenced by warping of the wood veneer surface coverings. To minimize warpage under prior constructions, such sheets of wood veneer are bonded or adhesively secured to a relatively thick, rigid particle board, for example, having a thickness of one-half inch. As a result, prior proposed wood veneer laminate panels have included a relatively thick dimension and are unsuitable for very thin panels desired for covers for books, folios, notebooks, and the like.
It should be noted that thin wood veneer sheets include variable wood grain patterns and within the area of the sheet, the wood grain and its characteristics, such as light and dark sections, soft and hard sections, knots, and the like, provide different reactions to changes in moisture conditions present in the wood veneer and to changes in the degree of humidity in the ambient atmosphere. Wood has strength and hardness characteristics which may cause dimensional instability of the wood veneer sheet and in very thin panels, may result in distortion, warping, twisting, and cupping of a thin laminate panel. Instability of such a thin panel is produced by differences, between the panel and atmosphere, in temperature, humidity or moisture, and vapor pressures relating thereto. A thin veneer panel is particularly sensitive to such ambient conditions.